Drive apparatus of liquid crystal panel and liquid crystal display apparatus

Abstract

[Object]To provide a liquid-crystal display using liquid crystal having splay alignment and bend alignment, which prevents irregularity of a display screen after power off and quickly transfers the liquid-crystal layer of a liquid-crystal panel to bend alignment. [Solving Means] A liquid-crystal panel drive 100 including an output system 102 of selectively outputting one voltage from a video signal voltage Vcom, a reset voltage Vsc, and transfer voltage of transferring the liquid-crystal panel from splay alignment to bend alignment, and control means 103 , wherein the reset voltage is applied before applying the video signal voltage Vcom in the power-on state and thereafter the transfer voltage is applied, the transfer voltage is applied to the liquid-crystal panel in the power-off state, and then the reset voltage is applied and thereafter supply of a voltage to the liquid-crystal panel is stopped.

1 . A driving device for applying a voltage to a liquid-crystal panel having a liquid-crystal layer capable of being a splay alignment state or a bent alignment state, comprising: 
 a voltage output means of outputting at least one voltage selected from voltages including a video signal voltage, a reset voltage, and a transfer voltage for transiting the liquid-crystal panel from the splay alignment to the bend alignment, in accordance with power-off or power-on state of the liquid-crystal display panel, wherein    the voltage output means applies the reset voltage and then transfer voltage to the liquid-crystal display panel in this order before applying the video signal voltage at the power-on state, and applies the transfer voltage and then the reset voltage in this order before stopping to apply voltages at the power-off state.    
     
     
         2 . A driving device for applying a voltage to a liquid-crystal panel having a liquid-crystal layer capable of being a splay alignment state or a bent alignment state, comprising: 
 a voltage output means of selectively outputting one voltage from a plurality of voltages including at least a video signal voltage, a reset voltage, and a transfer voltage for transiting the liquid-crystal panel from the splay alignment state to the bend alignment; wherein    a first period of selecting the reset voltage and a second period of selecting the transfer voltage after the first period are successively set based on an on-signal of the liquid-crystal panel input from the outside, and    a third period of selecting the transfer voltage and a fourth period of selecting the reset voltage after the third period are successively set based on an off-signal of the liquid-crystal panel input from the outside.    
     
     
         3 . A driving device for applying a voltage to a liquid-crystal panel having a liquid-crystal capable of being a splay alignment or a bent alignment comprising: 
 a first driving circuit connected to one-hand electrode of the liquid-crystal panel to selectively apply a transfer voltage of transiting the liquid-crystal panel from the splay alignment to the bend alignment, a video signal voltage, and a reset voltage;    a second driving circuit connected to the other-hand electrode of the liquid-crystal panel to selectively apply a constant potential; and    a control circuit of controlling operations of the first driving circuit and the second driving circuit depending on a power-off signal or power-on signal of the liquid-crystal panel input from the outside; wherein    the control circuit controls the first driving circuit so as to set a first period for selecting the reset voltage, second period for selecting the transfer voltage, and third period for selecting the video signal voltage in this order based on the on-signal, and so as to set a fourth period for selecting the transfer voltage and fifth period for selecting the reset voltage in this order.    
     
     
         4 . The liquid-crystal panel driving device according to any one of  claims 1  to  3 , wherein 
 the reset voltage has an absolute value smaller than that of the transfer voltage.    
     
     
         5 . The liquid-crystal panel driving device according to  claim 1 , wherein 
 the voltage output means applies a predetermined video signal voltage to become substantially uniform to each pixel of the liquid-crystal panel between application of the transfer voltage and application of the reset voltage in the power-off state.    
     
     
         6 . The liquid-crystal panel driving device according to  claim 3 , wherein 
 the control circuit performs the control so as to insert a sixth period for applying a predetermined video signal voltage to become substantially uniform to each pixel of the liquid-crystal panel between the fourth period and the fifth period in the power-off state.    
     
     
         7 . The liquid-crystal pane driving device according to  claim 5  or  6 , wherein 
 the substantially-uniform predetermined video signal voltage is for displaying Black display on the liquid-crystal panel.    
     
     
         8 . The liquid-crystal panel driving device according to  claim 7 , wherein 
 the reset voltage applied in the power-off state of the liquid-crystal panel is a video signal voltage is for displaying White display on the liquid-crystal panel.    
     
     
         9 . The liquid-crystal panel driving device according to  claim 7 , wherein 
 the reset voltage selected in the fifth period is a video signal voltage is for displaying Black display on the liquid-crystal panel.    
     
     
         10 . The liquid-crystal panel driving device according to  claim 1 , wherein 
 the reset voltage applied in the power-on state of the liquid-crystal panel is a video signal voltage is for displaying Black display on the liquid-crystal panel.    
     
     
         11 . The liquid-crystal panel driving device according to  claim 2 , wherein 
 the reset voltage selected in the first period is a video signal voltage is for displaying Black display on the liquid-crystal panel.    
     
     
         12 . The liquid-crystal panel driving device according to  claim 1 , wherein the voltage output means comprises; 
 a first selection switch to which the video signal voltage and the reset voltage are input and either of them is output,    a second selection switch to which the positive transfer voltage and the negative transfer voltage are input and either of them is output, and    a third selection switch to which outputs of the first selection switch and the second selection switch are input and either of them is output.    
     
     
         13 . A liquid-crystal display device comprising: 
 the liquid-crystal panel driving device of any one of  claims 1  to  3 ;    a liquid-crystal panel having a liquid-crystal layer using OCB-mode liquid crystal; and    a driver of receiving the voltage from the liquid-crystal panel drive and making the liquid-crystal panel perform display.